Is treating a bad father well out of fear of God considered hypocrisy, and what is the ruling of Islamic law regarding a father who combines prayers under the pretext of traveling a distance that permits shortening prayers?

The right of the father is great, and one must show piety and kindness towards him, even if he is unjust. This is not hypocrisy. He should be advised gently and respectfully, or one can seek the help of some righteous people, while frequently supplicating for him. As for combining and shortening prayers during travel, the preponderant opinion is that the travel which permits this is a distance of approximately 83 kilometers. Shortening prayers is not permissible if the sole purpose of travel is to avail oneself of the concession.